Thanks everyone! After extensive research, I found that there is a ride next to the amusement park (panaramic area). The ride is called "Talaia", which takes you 550 above sea level. From there you can take a really nice picture of the church.

Hát elég bonyi volt az út oda, azt írta a google hogy gyalog is ugyanannyi idő lett volna, de felfele még busszal mentünk mert lefelére hagytuk a sétálást. A városból S1 vonattal a Baixador de Vallvidreraig kell menni, onnan 118-as busszal Vallvidrera felé a Placa de Vallvidreraig, innen 111-es busszal kell menni ami már a templomnál tesz le. Ez T-10es gyűjtőjeggyel 1jegy/fő.

There is a regular bus service up there even when the amusement park is closed. The number of the bus service is 111. Please note that the church isn't open to visitors until 11 am. I was lucky enough to be staying next door, so visited quite frequently during my 5 day stay.

I think you can visit the terrace with a dog.

Come per tutte le chiese, c'è un "dress code" da rispettare. Le scarpe non sono un problema, i pantaloncini al ginocchio neanche a meno che non siano degli shorts da spiaggia.

The terrace is free to visit there is a charge if you want to go up the church tower, just buy that on the day. There is a charge for the funicular railway and tram or bus that you have to use to get to the top of the hill where the terrace is situated.

Mi pare sia gratuita

Hi, we went by car but you can take the bus T2A from Placa Catalunya, Barcelona's main square up to Tibidabo hill where the church is located.